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87 lines
3.0 KiB
Markdown
87 lines
3.0 KiB
Markdown
---
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machine_translated: true
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machine_translated_rev: 72537a2d527c63c07aa5d2361a8829f3895cf2bd
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toc_priority: 42
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toc_title: mysql
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---
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# mysql {#mysql}
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允许 `SELECT` 要对存储在远程MySQL服务器上的数据执行的查询。
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``` sql
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mysql('host:port', 'database', 'table', 'user', 'password'[, replace_query, 'on_duplicate_clause']);
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```
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**参数**
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- `host:port` — MySQL server address.
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- `database` — Remote database name.
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- `table` — Remote table name.
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- `user` — MySQL user.
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- `password` — User password.
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- `replace_query` — Flag that converts `INSERT INTO` 查询到 `REPLACE INTO`. 如果 `replace_query=1`，查询被替换。
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- `on_duplicate_clause` — The `ON DUPLICATE KEY on_duplicate_clause` 表达式被添加到 `INSERT` 查询。
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Example: `INSERT INTO t (c1,c2) VALUES ('a', 2) ON DUPLICATE KEY UPDATE c2 = c2 + 1`, where `on_duplicate_clause` is `UPDATE c2 = c2 + 1`. See the MySQL documentation to find which `on_duplicate_clause` you can use with the `ON DUPLICATE KEY` clause.
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To specify `on_duplicate_clause` you need to pass `0` to the `replace_query` parameter. If you simultaneously pass `replace_query = 1` and `on_duplicate_clause`, ClickHouse generates an exception.
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简单 `WHERE` 条款如 `=, !=, >, >=, <, <=` 当前在MySQL服务器上执行。
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其余的条件和 `LIMIT` 只有在对MySQL的查询完成后，才会在ClickHouse中执行采样约束。
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**返回值**
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与原始MySQL表具有相同列的table对象。
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## 用法示例 {#usage-example}
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MySQL中的表:
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``` text
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mysql> CREATE TABLE `test`.`test` (
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-> `int_id` INT NOT NULL AUTO_INCREMENT,
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-> `int_nullable` INT NULL DEFAULT NULL,
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-> `float` FLOAT NOT NULL,
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-> `float_nullable` FLOAT NULL DEFAULT NULL,
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-> PRIMARY KEY (`int_id`));
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Query OK, 0 rows affected (0,09 sec)
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mysql> insert into test (`int_id`, `float`) VALUES (1,2);
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Query OK, 1 row affected (0,00 sec)
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mysql> select * from test;
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+------+----------+-----+----------+
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| int_id | int_nullable | float | float_nullable |
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+------+----------+-----+----------+
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| 1 | NULL | 2 | NULL |
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+------+----------+-----+----------+
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1 row in set (0,00 sec)
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```
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从ClickHouse中选择数据:
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``` sql
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SELECT * FROM mysql('localhost:3306', 'test', 'test', 'bayonet', '123')
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```
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``` text
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┌─int_id─┬─int_nullable─┬─float─┬─float_nullable─┐
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│ 1 │ ᴺᵁᴸᴸ │ 2 │ ᴺᵁᴸᴸ │
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└────────┴──────────────┴───────┴────────────────┘
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```
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## 另请参阅 {#see-also}
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- [该 ‘MySQL’ 表引擎](../../engines/table-engines/integrations/mysql.md)
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- [使用MySQL作为外部字典的来源](../../sql-reference/dictionaries/external-dictionaries/external-dicts-dict-sources.md#dicts-external_dicts_dict_sources-mysql)
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[原始文章](https://clickhouse.tech/docs/en/query_language/table_functions/mysql/) <!--hide-->
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